Polyurethane and leather-like sheet utilizing the same

Abstract

A polyurethane composition suitable for producing leather-like sheets having a soft hand and excellent durability and being dyeable with acid dyes comprising a mixture of: a first polyurethane (a) obtained by reacting: an intermediate product diol (D) with both ends thereof substantially being OH and obtained by reacting a tertiary amino group-containing diol (A), a polymer diol (B) having a number average molecular weight of 500 to 3,000 selected from the group consisting of polyesters, polycarbonates, polylactones and polyethers and an organic diisocyanate (C1), in such stoichiometric amounts as to make the molar ratio of NCO/OH 0.5 to 0.99, a low molecular weight diol (E), and diphenylmethane-4,4'-diisocyanate (C2), and a second polyurethane (b) having a solubility in toluene of not more than 50% by weight and obtained by reacting a polymer diol having structural units from dimethylsiloxane and a second organic diisocyanate and having a number average molecular weight of 1,000 to 10,000, the ratio of said second polyurethane (b) to said first polyurethane (a) being in a range of 0.5 to 50% by weight.

What is claimed as new and desire to be secured by Letters Patent of the United States is: 
     
       1. A polyurethane composition comprising a mixture of a first and second polyurethane: wherein said first polyurethane (a) is obtained by reacting: an intermediate product diol (D) with both ends thereof consisting essentially of OH and obtained by reacting a tertiary amino group-containing diol (A), a polymer diol (B) having a number average molecular weight of 500 to 3,000 selected from the group consisting of polyesters, polycarbonates, polylactones and polyethers and an organic diisocyanate (C1), in such stoichiometric amounts as to make the molar ratio of NCO/OH 0.5 to 0.99,   a diol chain extender (E),   diphenylmethane-4,4'-diisocyanate (C2), and   said second polyurethane (b) has a solubility in toluene of not more than 50% by weight and obtained by reacting a polymer diol having structural units from dimethylsiloxane and an organic diisocyanate (C3) and having a number average molecular weight of 1,000 to 10,000,     the ratio of said second polyurethane (b) to said first polyurethane (a) being in a range of 0.5 to 50% by weight based on the first polyurethane (a).   
     
     
       2. A process for producing polyurethanes, which comprises combining a first polyurethane (a) obtained by reacting a tertiary amino group-containing diol (A), a polymer diol (B) having a number average molecular weight of 500 to 3,000 selected from the group consisting of polyesters, polycarbonates, polylactones and polyethers and an organic diisocyanate (C1), in such stoichiometric amounts as to make the molar ratio of NCO/OH 0.5 to 0.99, to obtain an intermediate product diol (D), and reacting the intermediate product diol (D), a diol chain extender (E), and diphenylmethane-4,4'-diisocyanate (C2),   with a second polyurethane (b) having a solubility in toluene of not more than 50% by weight and obtained by reacting a polymer diol having structural units from dimethylsiloxane and an organic diisocyanate (C3) and having a number average molecular weight of 1,000 to 10,000,   the ratio of said second polyurethane (b) to said first polyurethane (a) being in a range of 0.5 to 50% by weight based on the first polyurethane (a).   
     
     
       3. A synthetic leather sheet comprising: a fibrous base and   a polyurethane composition comprising a mixture of a first and second polyurethane, wherein said first polyurethane is obtained by reacting: an intermediate product diol (D) with both ends thereof consisting essentially of OH and obtained by reacting a tertiary amino group-containing diol (A), a polymer diol (B) having a number average molecular weight of 500 to 3,000 selected from the group consisting of polyesters, polycarbonates, polylactones and polyethers and an organic diisocyanate (C1), in such stoichiometric amounts as to make the molar ratio of NCO/OH 0.5 to 0.99,     a diol chain extender (E), and diphenylmethane-4,4'-diisocyanate (C2) and   a second polyurethane (b) having a solubility in toluene of not more than 50% by weight and obtained by reacting a polymer diol having structural units from dimethylsiloxane and a second organic diisocyanate (C3) and having a number average molecular weight of 1,000 to 10,000,   the ratio of said second polyurethane (b) to said first polyurethane (a) being in a range of 0.5 to 50% by weight based on the first polyurethane (a).   
     
     
       4. The polyurethane according to claim 1, wherein said polymer diol (B) is a polyester obtained from an aliphatic dibasic acid having 4 to 8 methylene chain carbon atoms and an aliphatic diol having 4 to 9 main chain carbon atoms. 
     
     
       5. The polyurethane according to claim 1, wherein said polymer diol (B) is a polycarbonate obtained from an aliphatic diol having a 4 to 9 main chain carbon atoms. 
     
     
       6. The polyurethane according to claim 1, wherein said organic diisocyanate (C1) is at least one member selected from the group consisting of diphenylmethane-4,4'-diisocyanate, isophorone diisocyanate and 2,4-or 2,6-tolylene diisocyanate. 
     
     
       7. The process for producing polyurethanes according to claim 2, wherein said polymer diol (B) is a polyester obtained from an aliphatic dibasic acid having 4 to 8 carbon atoms and an aliphatic diol having 4 to 9 main chain carbon atoms. 
     
     
       8. The process for producing polyurethanes according to claim 2, wherein said polymer diol (B) is a polycarbonate obtained from an aliphatic diol having 4 to 9 main chain carbon atoms. 
     
     
       9. The process for producing polyurethanes according to claim 2, wherein said organic diisocyanate (C1) is at least one member selected from the group consisting of diphenylmethane-4,4'-diisocyanate, isophorone diisocyanate and 2,4-or 2,6-tolylene diisocyanate. 
     
     
       10. The synthetic leather sheet according to claim 3, wherein said polymer diol (B) is a polyester obtained from an aliphatic dibasic acid having 4 to 8 methylene chain carbon atoms and an aliphatic diol having 4 to 9 main chain carbon atoms. 
     
     
       11. The synthetic leather sheet according to claim 3, wherein said polymer diol (B) is a polycarbonate obtained from an aliphatic diol having a carbon chain length of 4 to 9. 
     
     
       12. The synthetic leather sheet according to claim 3, wherein said organic diisocyanate (C1) is at least one member selected from the group consisting of diphenylmethane-4,4'-diisocyanate, isophorone diisocyanate and 2,4-or 2,6-tolylene diisocyanate. 
     
     
       13. A process for producing suede tone synthetic leather sheets having a fibrous nap, which comprises impregnating a fiber entangled nonwoven fabric formed of ultrafine fiber generating fibers having a fineness of 2 to 15 deniers comprising a vinyl polymer with a solution of a polyurethane and wet coagulating the solution, to prepare a polyurethane-containing entangled nonwoven fabric, removing by extraction the vinyl polymer of the ultrafine fiber-generating fibers constituting the nonwoven fabric to convert the ultrafine generating fibers into ultrafine fibers of not more than 0.2 denier, and then treating the surface of the nonwoven fabric to form a napped surface and dyeing the nonwoven fabric; wherein said polyurethane is a mixed polyurethane composition comprising a mixture of a first and second polyurethane,   wherein said first polyurethane (a) is obtained by reacting:   an intermediate diol (D) with both ends thereof essentially being OH and obtained by reacting a tertiary amino group-containing diol (A), a polymer diol (B) having a number average molecular weight of 500 to 3,000 and selected from the group consisting of polyesters, polycarbonates, polylactones and polyethers, and an organic diisocyanate (C1), in such stoichiometric amounts as to make the molar ratio of NCO/OH 0.5 to 0.99, a diol chain extender (B), and   diphenylmethane-4,4'-diisocyanate (C2), and   said second polyurethane (b) has a solubility in toluene of not more than 50% by weight and is obtained by reacting a polymer diol having structural units from dimethylsiloxane and an organic diisocyanate (C3) and having a number average molecular weight of 1,000 to 10,000,     the ratio of said second polyurethane (b) to said first polyurethane (a) being in a range of 0.5 to 50% by weight based on the first polyurethane (a).